Load handling in forklift trucks

ABSTRACT

A slope-piling arrangement for a forklift truck in which one of the lifting forks has its vertical leg movably engaged with the fork apron so that the fork leg, during movement relative to the apron, is constrained to move vertically, and in which a power drive mechanism is connected between the apron and the fork for moving the fork relative to the apron.

United States Patent Inventor Thomas N. Melin 1424 24th Ave., Longview,Wash. 98632 Appl. No 801,137 Filed Feb. 20, 1969 Patented June 29, 1971Continuation-impart of application Ser. No. 439,846, Mar. 15, 1965, nowPatent No. 3,429,470.

LOAD HANDLING 1N FORKLIFT TRUCKS 4 Claims, 10 Drawing Figs.

US. Cl 214/731, 214/750, 214/1 Int. Cl B661 9/12 FieldolSe-rch 214/730,731, 750, 702

Primary ExaminerGerald M. F orlenza Assistant Examiner-Robert J. SparAttorney-Christie, Parker & Hale References Cited UNITED STATES PATENTSJannsen Skutle et al.

Lull Erickson et al.

Drakulich Gibson et al Houseman et a1.

214/750 214/731 214/731 X 214/660 214/731 X 214/731 X 214/731 ABSTRACT:A slope-piling arrangement for a forklift truck in which one of thelifting forks has its vertical leg movably engaged with the fork apronso that the fork leg, during movement relative to the apron, isconstrained to move vertically, and in which a power drive mechanism isconnected between the apron and the fork for moving the fork relative tothe apron.

LOAD HANDLING IN FORKLIFT TRUCKS CROSS-REFERENCE TO RELATED APPLICATIONSThis application is a continuation-in-part of copending application Ser.No. 439,846 filed Mar. 15, 1965 and issued Feb. 25, 1969 as US. Pat. No.3,429,470.

FIELD OF THE INVENTION This invention relates to forklift trucks. Moreparticularly, it relates to apparatus adjustably interconnecting thelifting forks of forklift trucks with the fork apron so that a load carried on the forks may be lifted from or deposited on loadreceiving meansangled out of the horizontal with respect to the truck chassis.

BACKGROUND OF THE INVENTION In load handling with forklift trucks, theload is supported on a pair of forks which extend forwardly from avertically movable apron mounted to the front end of the vehicle.Usually the load is lifted from or deposited on a foundation or the likedefining a load-receiving plane parallel to the surface which supportsthe truck. Often, however, the surface upon which the load is to bedeposited, or from which the load is to be lifted, is not parallel tothe floor or other surface which supports the truck. In such cases, theforks cannot be engaged with load without damaging the load and/or thetruck, or the load cannot be deposited without damage to the truck, tothe load, or to the load-receiving structure.

This invention provides simple, effective and economic apparatus whichadjustably interconnects at least one of the forks of a forklift truckto the fork apron for vertical movement of the fork relative to theapron and relative to the other fork. Existing trucks can be modified toreceive this apparatus. Moreover, the apparatus can be incorporatedreadily into the design of a truck during manufacture of the truck. Theapparatus has the feature that its use does not increase the off set ofthe truck, thereby assuring that the load-handling capacity of the truckis essentially undiminished. The offset of a forklift truck is thedistance between the center of the front axle of the truck and the frontsurface of the fork apron. Such apparatus is referred to herein as aslope-piling apparatus. As used in this specification and in theappended claims, the term slope-piling apparatus" refers to apparatus bywhich a forklift truck is capable of lifting a load from, or depositinga load on, a surface which is angled, in a direction only transverselyof the truck, relative to a surface on which the truck is disposed.

SUMMARY OF THE INVENTION Generally speaking, this invention provides aslope-piling apparatus for a forklift truck. The forklift truck forwhich the slope-piling apparatus is provided includes a chassis, a forkapron mounted for controlled vertical movement relative to the chassis,and a pair of load-bearing fork members extending from the fork apron.The slope-piling apparatus comprises means mounting one of the forkmembers for guided movement vertically of the fork apron, andcontrollable means operatively coupled between the fork apron and theone fork member for moving the one fork member vertically relative tothe fork apron and the other fork.

DESCRIPTION OF THE DRAWINGS The above-mentioned and other features ofthe invention are more fully set forth in the following detaileddescription of the invention presented in conjunction with theaccompanying drawings, wherein:

FIG. 1 is a front elevation view of the fork apron of a forklift truckequipped with apparatus according to this invention;

FIG. 2 is a side elevation view of the structure shown in FIG.

FIG. 3 is a fragmentary front elevation view of another apparatusaccording to this invention and which is claimed in the above-referencedpatent;

FIG. 4i is a fragmentary front elevation view, with parts broken away,of still another apparatus according to this invention;

FIG. 5 is a fragmentary side elevation view of another slopepilingdevice according to the invention;

FIG. 6 is a rear elevation view taken along line 6-6 in FIG.

FIG. 7 is a side elevation view of still another slope-pilingarrangement;

FIG. 8 is a side elevation view of yet another slope-piling apparatus;

FIG. 9 is a rear elevation view taken along line 9-9 in FIG. 8; and

FIG. 10 is a fragmentary front elevation view of still anotherslope-piling apparatus.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS FIGS. l and 2 show a forkapron 10 mounted for vertical movement to an elevator 11 which isconnected to the front end of the chassis 12 of a forklift truck 13. Theelevator typically includes two pairs of channel members 14, I5. Outerchannels 15 are pivoted to the truck chassis by pins 16, and innerchannels 114 have their upper ends connected together by a bridge (notshown) and are mounted to channels 15 by rollers (not shown) forvertical movement relative to the outer channels. A hydraulic ram 117 isalso connected to the chassis at its lower end and is connected to thebridge at its upper end. A length of chain 18 is connected at one end tothe fork apron and passes over a pulley (not shown) mounted to thebridge. The other end of the chain is fixed relative to the chassis. Thefork apron carries rollers 19 which are engaged between the flanges ofthe inner channels to mount the apron to the elevator. As ram 17 isextended, the apron is moved vertically an amount double the extensionof the ram. The truck chassis is supported on ground 20 by wheels 21.The details of the elevator and its drive mechanism are not part of thisinvention which resides in the structure mounting the forks (describedbelow) to the fork apron.

Fork apron 10 includes upper and lower crossmembers 22 and 23,respectively, side members 24, and vertical intermediate members 25. Apair of fork members 26, 27 are carried by the fork apron. Fork member26 has a vertical leg 28 and a horizontal leg 29, the latter leg beingthe fork tine upon which a load is engaged when the truck is in use.Fork member 26 is secured to the fork apron by a horizontal hanger rod30 mounted to apron upper member 22 and passed through a hole 311 in theupper end of the vertical leg of the fork member. Fork member 26,therefore, is not movable vertically relative to the fork apron. Therear surface of the fork member bears against the front face of theapron lower member.

A conventional forklift truck usually has two fork members generallylike those described above, both of which normally are secured to a forkapron in the same manner that fork member 26 is secured to apron 10, orin an equivalent manner. Those skilled in the art, however, will readilyappreciate that the manner in which fork member 26 is connected to apronis not a part of this invention, and is described above merely for thepurpose of a complete explanation of the invention.

Fork member 27, however, is mounted to the fork apron for movementvertically relative to the apron. This fork member has a vertical leg 32and a horizontal leg or tine 33 like fork member 26. The upper rearportion of vertical leg 32 defines a boss 34 through which is formed avertically elongated slot 35 extending parallel to the front surface ofthe leg. Hanger bar 30 passes through the slot and cooperates with theslot to guide the fork member in vertical movement relative to theapron.

The slope-piling apparatus also includes means for moving fork member 27vertically relative to the fork apron. A hydraulic ram assembly 36 hasone end pivotally connected to lower apron member 23 and its other enddisposed between and pivotally connected to a pair of lugs 37 secured tothe rear side of vertical fork member leg 32 adjacent the lower end ofboss 34. The ram preferably is a double-acting ram and is operated byhydraulic fluid supplied to the ram assembly through ducts 38 and 39.The nature of fluid flow through the ducts is controlled by the operatorof the truck, thereby controlling the operation of the ram. It will bereadily apparent to those skilled in the art that mechanisms differentfrom that described, for example, ajackscrew, may be used to move thefork member vertically relative to the fork apron.

FIG. 3 illustrates another form which structure according to thisinvention may take. A fork member 40 has a vertical leg 41 and ahorizontal leg or load-bearing tine (not shown). The upper rear portionof the vertical leg defines a boss (not shown in FIG. 3 but similar toboss 34 shown in FIG. 2 as a part of fork member 27) through whichextends a vertically elongated slot 42. The slot traverses the bossparallel to the front surface of the fork member vertical leg. Ahorizontal hanger bar 43 extends through slot 42 and has its endssupported in a pair of vertical members 44 in a fork apron 45. The forkapron also includes an upper transverse member 46 to which verticalmembers 44 are connected. The upper transverse member of the fork apronhas an aperture 47 formed through it above the fork member. The apertureis large enough to permit the upper end of the fork member vertical legto be moved through it. Aperture 47, slot 42 and hanger bar 43 cooperatewith each other to guide the fork member in vertical movement relativeto the fork apron.

An elongated vertical notch 48 is formed in the upper end of fork membervertical leg 41 and extends from front to back of the leg. A hydraulicram assembly 49 is disposed in the notch and has one end secured to thefork member. The other end of the ram assembly is secured to a sleeve 50which journals the hanger bar in notch 48. The ram is operated to movethe fork member upwardly and downwardly relative to apron 45. Motivefluid is supplied to the ram assembly through ducts (not shown) whichconnect the ram assembly to a suitable control at the truck operator'sstation.

FIG. 4 shows yet another structural arrangement of slope pilingapparatus according to this invention. Fork apron 52 includes atransverse upper member 53, a pair of vertical members 54 secured to theupper member, and a crossmember 55 disposed below the upper member andextending between and secured to the vertical members. A fork member 56has a vertical leg 57 and a horizontal leg or tine (not shown). Theupper end of the fork member vertical leg has a hole 58 formed throughit from side to side of the leg parallel to the forward surface of theleg. The hole is horizontal and receives a hanger rod 59, the ends ofwhich extend laterally of the fork member. The ends of the hanger rodare slidably received in respective ones of a pair of verticallyelongated slots 60 formed through the apron vertical members adjacentthe apron upper member. The hanger rod and slots 60 cooperate to guidethe fork member in vertical movement relative to the fork apron.

A hydraulic ram assembly 61 is coupled between the fork apron and thehanger rod. One end of the ram assembly, preferably cylinder 62, issecured to apron crossmember 55. The other end of the ram assembly,preferably the outer end of piston 63, is connected to a yoke member 64which extends from adjacent one side of the fork member vertical legaround behind the leg to the other side of the fork member as shown inFIG. 4. The ends of the yoke member are secured to respective ones of apair of sleeves 65 which journal hanger rod 59 between the fork memberand apron vertical members 54. Operation of the ram assembly is producedby hydraulic fluid supplied to the ram assembly through supply ducts 66and 67 at the control of the operator of the truck.

Preferably the apron crossmember defines therein a forwardly openingnotch 68 which has a width slightly greater than the width of the forkmember vertical leg. Notch 68 provides a further guide mechanism for thefork member as it is moved vertically relative to the fork apron inresponse to controlled operation of ram assembly 61.

FIGS. 5-10 illustrate other embodiments of slope-piling mechanismsaccording to this invention. FIGS. 5 and 6 show a fork apron 70 to whichone fork member 71 is mounted for vertical movement relative to a secondfork member (not shown) which may be mounted to the apron in any mannerdesired, such as the manner in which fork member 26 is mounted to apronl0. Fork member 71 has a load supporting horizontal leg 72 and avertical leg 73 which is movably engaged for guided movement in avertical passage 74 defined by the apron. In the vicinity of the movablefork member, the apron has a front plate 75, a backplate 76 andlaterally spaced spacer plates 77 and 78, the latter extendingvertically of the apron between the frontand backplates. Plates -78define the boundaries of passage 74 which has a cross-sectionalconfiguration conforming to that of the vertical leg of the fork memberand which is sized to loosely receive and yet adequately guide thevertical leg. A power drive mechanism 79 is coupled directly between theapron and the fork member for moving the fork member vertically relativeto the apron; the capacity of the drive mechanism is sufficient to movethe fork member even when the movable fork member cooperates with theother fork member to support a load up to and equal to the rated loadcapacity of the forklift truck of which apron 70 is a component. Asshown in FIGS. 5 and 6, the drive mechanism preferably is adouble-acting hydraulic ram 80 pivotally connected between a lug 81secured to the rear surface of backplate 76 and a lug 82 secured to therear of the vertical leg of the fork member adjacent the junctionbetween the vertical and horizontal legs of the fork member. The ram isconnected to the hydraulic control system of the forklift truck bysuitable hydraulic lines 83 and 84 so that, upon actuation of the ram inthe appropriate direction, the fork member is driven in guided movementrelative to the apron. To maximize the guiding engagement of the apronwith fork member leg 73 and also to maximize the range through which thefork member may be moved relative to the apron, a downwardly open slot85 is formed in the lower edge of back plate 76 centrally between spacerplates 77 and 78 to accommodate lug 82.

FIG. 7 is a side elevation view of a slope-piling arrangement which issimilar to that shown in FIGS. 5 and 6, but in which apron does notdefine an enclosing passage for the vertical leg 91 of a fork member 92which also has a load-supporting horizontal leg 93. Apron 90 includes apair of spacer plates 94 and 95 which are arranged similar to spacerplates 77 and 78 of apron 70; the front and rear edges of the spacerplates lie forwardly and rearwardly, respectively, of the correspondingsurfaces of the fork member vertical leg, as shown. A front keeper bar96 is connected between spacer plates 94 and 95 adjacent the upperextent of the apron to slidably engage and constrain the front surfaceof the fork member vertical leg. A rear keeper bar 97 is connectedbetween the spacer plates adjacent the lower extent of the apron toslidably engage and constrain the rear surface of fork leg 91. Plates 94and 95 and keeper bars 96 and 97 define an open passage along which thevertical leg is guided when a drive mechanism, such as a double-actinghydraulic ram 98 having supply lines 99 and 100, is operated. Ram 98 isconnected between a lug 101 secured to the upper rear extent of thevertical leg and a lug 102 secured to the rear surface of rear keeperbar 97. The capacity of ram 98 should be as described concerning ram 80.

It will be apparent that, regardless of whether a load is supported bythe horizontal leg of fork member 92, the fork member, by reason of itsown weight and geometry, engages the front and rear keeper bars in themanner indicated by the arrows in FIG. 7. Thus, the described structureis effective to both support and guide the fork member during use of theforklift truck of which the apron is a component. it will also be seenthat ram 98'is connected between the apron and the movable fork memberin such manner to maintain and even augment proper engagement of thefork member with the keeper bars.

The embodiment shown in FIGS. 8 and 9 includes front and rear keeperbars 105 and 106 which are secured to the front and rear surfaces of thevertical leg 107 of a fork member 108 having a horizontalload-supporting leg 1109. Vertical leg 107 cooperates within a verticalpassage lllll formed within apron 110 which has a backplate 112 having arear surface substantially coplanar with the rear surface of thevertical leg; the apron has a front plate (not shown), the front surfaceof which is substantially coplanar with the front surface of verticalleg 107 on opposite sides of the passage. The keeper bars extendlaterally in opposite directions of the sides of the fork membervertical leg to slidably engage the exterior surfaces of the apronfrontand backplates and to transfer the loads of and applied to the forkmember to the apron. A double-acting hydraulic ram 1M, comprising powerdrive means for the slope-piling mechanism shown in FIG. 9, is connectedbetween lugs 115 secured to the lower rear extent of vertical leg 107and a bar 116 which extends parallel to the backplate and is supportedon opposite sides of the passage by lugs 117 secured to the backplate.Ram ll 14 is connected to the forklift truck hydraulic system bysuitable hydraulic lines lllltl and 119. Upon application of a load W(FIG. 9) to the fork member, the keeper bars are forcibly engaged withthe apron as shown by the arrows in FIG. 9. The embodiment shown inFIGS. 8 and 9 operates according to much the same set of principles asare applicable to the operation of the embodimerits shown in FIGS. 57.

The embodiments described above and shown in FIGS. l- 9 involve, inbasic terms, structure in which only one of two load-handling forkmembers is vertically movable relative to a supporting elevatable apron;it will be appreciated, however, that both forks may be movablevertically relative to the apron without departing from the scope of theinvention. The embodiment shown in FIG. provides two vertically movableforks which are interconnected to move simultaneously equal amounts inopposite directions upon operation of the power drive mechanismassociated with the forks.

Thus, as shown in FIG. 10, a pair of lifting fork members 125 and 126,each having a vertical leg 127 and a horizontal leg 128, are associatedwith an elevatable fork apron 129 in a forklift truck, such as truck 13.The forks are disposed forwardly of an apron front plate 130 and arelocated adjacent the left and right ends of the apron as viewed in FIG.10. Each fork is engaged with a separate hanger bar 1131 and 132 in themanner described above relative to fork 26. The hanger bars aresupported at their juxtaposed ends in corresponding ones of a pair ofsupport blocks 133 and 134 secured to the apron front plate. The barscooperate in oversized holes 135 formed through the blocks. The adjacentends of the bars define rounded heads 136 which may abut each other asshown in FIG. 10.

The opposite ends of each of the hanger bars, outwardly of thecorresponding fork member, carry a roller 13.8 which is engaged with abearing plate 139 secured to the apron, preferably in the adjacent uppercorner of the apron. A suspension link 140 is associated with eachhanger bar and has its lower end connected to the bar, preferablybetween the corresponding fork member and the corresponding roller. Theother end of each suspension link is pivotally connected to acorresponding bellcrank 1412, the bellcranks being spaced from eachother along the length of the apron and pivotally mounted to the apronat 143 and 1%, respectively. The bellcranks are pivotally interconnectedby a connecting rod 145.

A drive mechanism Mi", such as a double-acting hydraulic .am 148 havingsuitable hydraulic lines 149 and 150 connecting it to the hydraulicsystem of the forklift truck, is connected between one of the bellcranksand the apron for driving the forks upwardly and downwardly relative tothe apron. Operation of the drive mechanism, because of the arrangementof the bellcranks as shown in FIG. 10, causes forks and 126 to moveequally in opposite directions relative to the apron, thereby tocontrollably adjust the angular relation of a load supported on theforks relative to the apron about an axis normal to the apron frontplate. During such movement of the forks, the hanger bars pivot relativeto the apron about pivot points 151, and the rollers roll along bearingplates 139.

The utility of slope-piling apparatus according to this invention isapparent from the following description of the operation of theembodiment shown in FIGS. 1 and 2. Let it be assumed that the forklifttruck is supported on a horizontal surface such as ground 20, and thatfork member 27 is positioned so that its horizontal leg is disposed inthe same horizontal plane as the horizontal leg of fork member 26. Thisis the usual position of the vertically movable fork member. Let it alsobe assumed that the operator of the truck desires to engage the forktines under a pallet upon which a load is supported so that the loadedpallet can be lifted and moved by the truck, but that the pallet isresting on a surface which is inclined to the horizontal across thetruck at an angle A (see FIG. 1 which is of such magnitude that bothforks cannot be engaged under or within the pallet. If the truck weremoved forward in an attempt to engage the forks with the pallet, one orthe other or both the fork members would engage the pallet structure,the load on the pallet, or the structure upon which the pallet issupported; such engagement of the forks with any of these things woulddamage the structure so engaged and might damage the truck itself. Toavoid this result, the operator of the truck merely operates ram 36 toraise or lower the movable fork member an amount sufficient to locateboth fork members in a plane parallel .to the surface on which thepallet is supported; vertical correspondence of these planes can beachieved by raising or lowering the fork apron. The forks can then beengaged with the pallet with ease, and the pallet can then be lifted andplaced in a horizontal condition by returning the movable fork member toits normal position.

If a load supported on the fork members is to be deposited on a surfacewhich is inclined across the truck relative to the surface on which thetruck is supported, the process described above can be reversed. It ispreferred that the forks be placed in a plane parallel to the surfaceupon which the load is to be deposited before the apron is lowered sothat the weight of the load will be uniformly distributed over thereceiving structure as the load is deposited. If a conventional forklifttruck having forks fixed vertically relative to the fork apron were usedin the situation described, the forks could not be withdrawn from underthe load without damage to the load, to the load receiving structure, orto the forks.

As indicated above, the vertically movable fork member in slope-pilingapparatus according to this invention normally is positioned at themidpoint of its range of vertical movement relative to the fork apron;the structure for moving and for guiding the movable fork member isarranged so that the tine of the movable fork member is then disposed inthe same horizontal plane as the tine of the other fork member, assumingthe truck itself is horizontal. Such a normal position of the movablefork member enables the fork to be moved either up or down as required.This normal position of the movable fork member also means that only asingle movable fork is required to provide a truck capable of lifting ordepositing loads on surfaces inclined either way across the truckrelative to the surface on which the truck itself is located. Obviously,however, as shown in FIG. 10, the truck could be provided with twovertically movable forks, which forks may or may not be operativelyinterconnected as shown in FIG. 10.

The invention has been described above in the context of specific typesof mechanisms and structural arrangements. Workers skilled in the art towhich the invention relates will recognize that modifications andalterations may be made in the mechanisms and structures describedwithout departing from the spirit of the invention. Accordingly, theforegoing description is not to be considered as limiting the scope ofthis invention.

What I claim is:

l. Slope-piling apparatus for a forklift truck having a fork apronextending transversely of the length of the truck and a pair ofload-bearing forks carried by the apron and extending forwardly of thechassis from the apron in spaced relation to each other, each of theforks having a vertical leg and a horizontal leg, the slope-pilingapparatus comprising means mounting the vertical legs of the forks tothe apron for guided movement vertically relative to each otherincluding a substantially horizontal elongate hanger bar for each forkaligned substantially perpendicular to the fork horizontal legs andfixed to the upper end of the vertical leg of the corresponding forkadjacent the end of the bar opposite from the other fork, meanspivotally mounting the other end of each bar to the apron, linkage meanscoupled between the hanger bars remote from said pivotally mountingmeans arranged to cause one fork to move vertically relative to theapron in response to vertical movement of the other fork relative to theapron an equal amount in the opposite direction, and controllable powermeans connected between the apron and the linkage means for moving thelinkage means in such manner as to move the hanger bars equally and tomove the forks equally vertically in opposite directions relative to theapron.

2. Slope-piling apparatus for a forklift truck having a fork apronextending transversely of the length of the truck and a pair of loadbearing forks carried by the apron and extending forwardly of thechassis from the apron in spaced relation to each other, at least one ofthe forks having a vertical leg which is movable relative to the apron,the slope-piling apparatus comprising means mounting the vertical leg ofthe one fork to the apron for guided movement vertically relative to theother fork including a substantially horizontal elongate hanger bar forthe one fork connected at one end thereof to the upper end of thevertical leg of the one fork, means pivotally mounting the other end ofthe hanger bar to the apron at a location on the apron between theforks, linkage means coupled to the hanger bar remote from saidpivotally mounting means arranged to cause the one fork to movevertically relative to the apron, and controllable power means connectedbetween the apron and the linkage means for moving the linkage means insuch manner as to pivotally move the hanger bar to move the one forkvertically in relation to the apron and to the other fork.

3. Slope-piling apparatus for a forklift truck having a fork apronextending transversely of the length of the truck and a pair ofload-bearing forks carried by the apron and extending forwardly of thechassis from the apron in spaced relation to each other, each of theforks having a vertical leg and a horizontal leg, the slope-pilingapparatus comprising means mounting the vertical legs of the forks tothe apron for guided movement vertically relative to each otherincluding substantially horizontal elongate hanger bar means for theforks aligned transversely of the apron substantially perpendicular tothe fork horizontal legs and at its opposite ends to the upper end ofthe vertical leg of the corresponding fork, means pivotally mounting thehanger bar means to the apron between the fork vertical legs, linkagemeans coupled to the hanger bar means remote from said pivotallymounting means arranged to cause the forks to move vertically relativeto the apron in opposite directions, and controllable power meansconnected between the apron and the linkage means for moving the linkagemeans to move the forks vertically in opposite directions relative tothe apron.

4. Slope-piling apparatus for a forklift truck having a fork apronextending transversely of the length of the truck and a pair ofload-bearing forks carried by the apron and extending forwardly of thechassis from the apron in spaced relation to each other, at least one ofthe forks having a vertical leg which is movable relative to the apron,the slope-piling apparatus comprising means mounting the vertical leg ofthe one fork to the apron for guided movement vertically relative to theother fork, linkage means coupled to the vertical leg of the one forkand operable to move the one fork vertically relative to the apron, andcontrollable linear motion power means disposed at the top of the apronwith the line of action thereof oriented substantially horizontal andconnected between the apron and the linkage means for operating thelinkage means to move the one fork vertically relative to the apron andto the other fork.

1. Slope-piling apparatus for a forklift truck having a fork apronextending transversely of the length of the truck and a pair ofload-bearing forks carried by the apron and extending forwardly of thechassis from the apron in spaced relation to each other, each of theforks having a vertical leg and a horizontal leg, the slope-pilingapparatus comprising means mounting the vertical legs of the forks tothe apron for guided movement vertically relative to each otherincluding a substantially horizontal elongate hanger bar for each forkaligned substantially perpendicular to the fork horizontal legs andfixed to the upper end of the vertical leg of the corresponding forkadjacent the end of the bar opposite from the other fork, meanspivotally mounting the other end of each bar to the apron, linkage meanscoupled between the hanger bars remote from said pivotally mountingmeans arranged to cause one fork to move vertically relative to theapron in response to vertical movement of the other fork relative to theapron an equal amount in the opposite direction, and controllable powermeans connected between the apron and the linkage means for moving thelinkage means in such manner as to move the hanger bars equally and tomove the forks equally vertically in opposite directions relative to theapron.
 2. Slope-piling apparatus for a forklift truck having a forkapron extending transversely of the length of the truck and a pair ofload bearing forks carried by the apron and extending forwardly of thechassis from the apron in spaced relation to each other, at least one ofthe forks having a vertical leg which is movable relative to the apron,the slope-piling apparatus comprising means mounting the vertical leg ofthe one fork to the apron for guided movement vertically relative to theother fork including a substantially horizontal elongate hanger bar forthe one fork connected at one end thereof to the upper end of thevertical leg of the one fork, means pivotally mounting the other end ofthe hanger bar to the apron at a location on the apron between theforks, linkage means coupled to the hanger bar remote from saidpivotally mounting means arranged to cause the one fork to movevertically relative to the apron, and controllable power means connectedbetween the apron and the linkage means for moving the linkage means insuch manner as to pivotally move the hanger bar to move the one forkvertically in relation to the apron and to the other fork. 3.Slope-piling apparatus for a forklift truck having a fork apronextending transversely of the length of the truck and a pair ofload-bearing forks carried by the apron and extending forwardly of thechassis from the apron in spaced relation to each other, each of theforks having a vertical leg and a horizontal leg, the slope-pilingapparatus comprising means mounting the vertical legs of the forks tothe apron for guided movement vertically relative to each otherincluding substantially horizontal elongate hanger bar means for theforks aligned transversely of the apron substantially perpendicular tothe fork horizontal legs and at its opposite ends to the upper end ofthe vertical leg of the corresponding fork, means pivotally mounting thehanger bar means to the apron between the fork vertical legs, linkagemeans coupled to the hanger bar means remote from said pivotallymounting means arranged to cause the forks to move vertically relativeto the apron in opposite directions, and controllable power meansconnected between the apron and the linkage means for moving the linkagemeans to move the forks vertically in opposite directions relative tothe apron.
 4. Slope-piling apparatus for a forklift truck having a forkapron extending transversely of the length of the truck and a pair ofload-bearing forks carried by the apron and extending forwardly of thechassis from the apron in spaced relation to each other, at least one ofthe forks having a vertical leg which is movable relative to the apron,the slope-piling apparatus comprising means mounting the vertical leg ofthe one fork to the apron for guided movement vertically relative to theother fork, linkage means coupled to the vertical leg of the one forkand operable to move the one fork vertically relative to the apron, andcontrollable linear motion power means disposed at the top of the apronwith the line of action thereof oriented substantially horizontal andconnected between the apron and the linkage means for operating thelinkage means to move the one fork vertically relative to the apron andto the other fork.